The Country Land and Business Association said it was confident in the ability of farmers and other rural businesses to create opportunities outside the EU.
CLA president Ross Murray said: "This is a historic decision and we are entering an unprecedented period for our country and economy.
"There will be a significant amount of change in the weeks, months and years ahead. This will bring challenges but also significant opportunities."
Mr Murray was speaking after the UK voted on Thursday (23 June) by 52% to 48% in favour of leaving the EU on a turnout of 72%.
"Millions of people have voted for a new and different future for the UK," he said.
:They have seen the opportunity to exploit new global markets, to reduce the red tape that stifles their ability to run their farm or business and to have a greater say in decisions that affect them and their rural communities.
"The CLA will be working to ensure that existing and future governments deliver on turning these desires into a reality."
With that in mind, some "some urgent decisions" must be made by government ministers, said Mr Murray.
"These decisions are necessary to secure the immediate future of the rural economy," he warned.
An early guaranteed was needed that Common Agricultural Policy support currently provided to UK farmers and the wider economy would continue unbroken and unchanged until at least the end of 2020.
"As negotiations begin on trade relationships to succeed our position as a full member of the European Union, ministers must have the needs of farming and other rural businesses at the front of their minds.
"The ambition must be a barrier and tariff-free relationship. Whatever happens, the UK Government must not allow a poor trade dynamic that leaves UK agriculture at a disadvantage."
Talks must begin as soon as practical on what will replace the support provided through the CAP, said Mr Murray.
"A dedicated UK agriculture and land use policy must be in place ready for the day we exit the European Union.
This has to be a widely accepted policy that supports our farmers, helping them to be resilient to unpredictable markets, and providing them with a firm foundation to compete with EU and other farmers from across the world.
"It must also be a policy that fully supports the vital work of managing our land and wildlife, preserving our landscapes and supporting rural communities."
Mr Murray said he had already written to Defra secretary Liz Truss, urging her to prioritise these decisions.